Wednesday, 12 August 2009

Take that leg off-It ain't mine

So I recently read this paper from V.S Ramachandran's group at the Salk Institute and came to realize how weird the field of cognitive neuroscience can really get. The paper is on Apotemnophilia (phew!! saying it is a task in itself), which yours truly had never heard of before. In any case, the disease is characterized by the desire to amputate one's own limb (Now how about that). These patients are otherwise mentally normal.

Individuals suffering from apotemnophilia always date the desire for amputation since childhood and often term the limb as being over-present or intrusive. Most obtain an amputation and paradoxically report feeling much more 'complete' and happier. Traditional explanations for the disease range from it being sexual paraphilia, related to the phallic resemblance of an amputee's stump (Someone get Freud in here!) or perhaps the mere sight of an amputee is permanently imprinted in the malleable psyche of a child as the "ideal body representation"

In this paper (McGeoch et. al (2009)), they demonstrate that the disease actually has a neurological basis based on the following observations:

1) Sufferers have no other psychological disorders

2) They desire an amputation of a limb at a specific level

3) There is a left sided bias.

The last observation points a finger to one particular area in the right parietal lobe called the superior parietal lobe (SPL) which receives connections from a host of other areas, namely the visual, primary somatosensory, secondary somatosensory, premotor and motor cortices. Additionally, the right parietal cortex is known to play a vital role in constructing body image and damage can lead to various disorders like somatoparaphrenia (denial of ownership of left arm) and others. The autors postulate that the right SPL may contain a hardwired representation of the body and if a particular limb were missing from the representation, the consequence may be a desire for amputation.

Right hemisphere of averaged control brain (a,b) and subject brain (c,d). Right SPL is outlined in black. Images a and c show touch to the left foot of control and subject respectively while b and d show touch to the right foot of control and subject respectively . This subject wanted right below-knee amputation (McGeoch et. al (2009))

This confirms the hypothesis that there is a congenital failure to represent affected limbs in the body image. Since visual and somatosensory inputs are still intact, but there is no corresponding limb representation, the result would be a mismatch that manifests itself as an intrusive and over-present limb.

6 comments:

It is worth nothing that Ramachandran is using the term "apotemnophilia" when every other researchers have accepted the term Body Integrity Identity Disorder (BIID). This is an important shift on two levels:

1- the 'philia' implies sexual gratification or motives. The majority of people who have BIID are not motivated by sexual needs to acquire a physical impairment.

and

2- there are other needs than the need for an amputation that fall under that term: some people need to be paralysed, others blind. Others yet need to be deaf.

I'd also like to correct a point you made. It is far from the majority of people with BIID who get their impairment. It is difficult and dangerous to get an amputation. Even more so to cause a spinal cord injury. Because the medical community is unwilling to accept surgery as a viable treatment option for BIID, we are left having to resort to self-injury, which doesn't always end well.

But of all the ones who *have* managed, they all report their lives have significantly improved, and they have no further desire to get other impairments.

Thanks for the comment Sean. Somatoparaphrenia is a type of BIID, where the subject refuses ownership of his or her own arm, but there is no sexual gratification involved. I suspect one reason for Apotemnophilia being a called a "philia" is because it may involve some kind of reorganization even in the sensory cortex, because if one looks at the sensory homunculus closely, one finds the legs next to the genitalia.

I wasn't aware of the complications arising out of an amputation. I guess, most of these people go underground and get amputations done from illegal or non-certified quacks (so to speak).

You said: "Somatoparaphrenia is a type of BIID". That is incorrect. BIID, as defined by the person who came up with the term, Dr. Michael First, includes only the need for amputation at the moment. Please do your research before making such statements!

The reason it was called apotemnophilia is because it was first named by Dr. John Money in the late '70s. Dr. Money saw most everything as sexual deviance, and is widely known for that.

As for getting an amputation... Only a few people have been able to get amputations on the black market. A few other people put their legs in dry ice until it froze solid, or used a shotgun or a chainsaw. Still, despite these "numbers", only a very minor percentage of people with BIID are able to acquire the body we require. I know this from having been involved in the BIID community for over 15 years now, from reading all the research currently available on the topic, from talking to researchers such as McGeoch, First, Dr. Chris Ryan, and many others, and finally, by speaking to people who have managed to become amputees.

It's great that you discuss this topic, I always like when more people explore this. But hazarding theories and stating erroneous facts is not particularly useful to anyone.

Hey, Sorry, I wrote the previous post in a hurry. I meant to write "Somatoparaphrenia is a type of monothematic delusion" and not "Somatoparaphrenia is a type of BIID" (I wasn't thinking :D) Just to point out, BIID itself is not always accompanied by a desire to amputate the limb, although the person continues to disown it. And also, most people with BIID don't report a sexual motivation. But the paralels are strikingly similar. Both somatoparaphrenia and apotemnophilia have a left sided preponderance, and in both cases, most individuals wants amputation at a particular level. You must be aware that somatoparaphrenia is usually a result of a stroke in the right parietal cortex. In fact, Ramachandran and McGeoch themselves hypothesize that a dysfunction in the right parietal lobe may not only be the cause of somatoparaphrenia but also BIID causing an uncoupling in the body's image. Hope that clears it up.

PS: You can trust me to do my research before I write something :) I'm a scientist myself

PPS: Nowhere in the original post have I either a) hazarded any theory or b) posted erroneous facts

a) If you are referring to the comment I posted where I said it would be interesting to look closely at the somatosensory cortex for any kind of reorganization because the leg lies close to the genitalia on the homunculus to test the "sexual gratification hypothesis" then note that I did not cite any article saying this which indicates that it is simply a thought from my end which I or someone else would like to look into. Whether you agree or disagree or have anything to say about it is completely up to you.

Hazarding a theory that is downright ridiculous would not be useful. If I said " apotemnophilia may arise due to liver cells migrating into the stomach" or some crap like that, it really doesn't serve the purpose and I should be laughed at. In any case, if this hypothesis has already been tested and disproved, then the matter ends here, but if it has never been tested or proved, then there is no reason to discount it. Remember the age old statement on which science has survived "The absence of proof is not proof of absence"

b) The main post has not a single erroneous fact. It is only a review of what has previously been published

Although I haven't been diagnosed with BIID. I have a strong, ultra-strong desire to be a left below the knee amputee. It has in fact been a desire of mine since I was about 10 years old.

I do not know why this is other than reading journals of biological and neurological studies on the subject.

I am not completely happy with out having an amputation. I cant explain it one bit. I dont know if it is wrong, I do not know if it makes me less of a person. But what I do know is no one knows it but me and now this forum.

Will I pursue an amputation probably not. However it happens I will not even be scared to go under the knife for a second. I would actually be excited and probably put on a drama that it sucks and so forth just to make others "know" im normal. I do not believe this is a disease as so many places put it. Is it any different that being a kid and wanting to be a Pilot or knowing that you were meant to be a great basketball player? Im sure an amputation is extreme but at the end of the day what is the difference.

BTW I have ZERO sexual desire or attraction to other amputees outside of the normal range of Physical and Emotional beauty in a woman. The amputation is just another person to me with something different. Noting special.

And whats funny as I have read in some writings that there is a preference for left side amputation. I have a strong desire for LEFT below knee.

I just broke my ankle really bad on that left side, I did not have surgery though, I have an extremely high tolerance for pain. However I wonder if further pain and damage leading to more pain and damage would be a permissible reason for amputation. If so I would opt for that any day against a corrective surgery.

I guess I might be insane. You can email me if you have questions or want to offer suggestion.